The measurement of an internal body temperature is useful for assessing the health of a subject. Body temperature is typically measured by a thermometer positioned in a human body cavity, such as the mouth, the axilla, or the rectum, or at an external site, such as the subject's forehead or temple. Invasive and non-invasive methods are also known for measuring core body temperatures in major organs of the body. Core body temperature is generally considered a better indicator of a subject's health than peripheral temperatures measured in body cavities or at external sites.
U.S. Pat. No. 6,280,397 ('397) to Yarden et al., whose disclosure is incorporated herein by reference, provides a device for estimating a core body temperature using an invasive temperature probe. The probe of '397 comprises first and second temperature sensors separated by thermal insulation thereby providing a means for measuring heat flux.
U.S. Pat. No. 6,292,685 to Pompei, whose disclosure is incorporated herein by reference, provides a method of detecting body temperature by laterally scanning an infra-red (IR) temperature detector across a forehead and providing a peak temperature from an area corresponding to a location of a temporal artery.
U.S. Pat. No. 6,794,990 to Tseng, whose disclosure is incorporated herein by reference, provides an electronic patch thermometer that communicates by wireless means to a receiver. The receiver generates a magnetic field transmission to provide power to the electronic patch thermometer.
U.S. Patent Publication 2006/0122473 to Kill et al., whose disclosure is incorporated herein by reference, provides an electronic thermometer that transmits a temperature signal to a receiver that in turn converts the signal to a format compatible with a monitor.
U.S. Patent Publication 2007/0194913 to Yokoshima et al., whose disclosure is incorporated herein by reference, provides a wireless temperature sensor module designed to be sealed within a container the size of a coin and to communicate temperature and patient information to a base station.
U.S. Pat. No. 6,220,750 to Palti, whose disclosure is incorporated herein by reference, discloses a method of measuring core body temperature by establishing a steady state of heat flow radiated from the surface of the body. External body temperatures are monitored at two points within an insulated space, one closer to the surface of the body and the second more distant from the surface of the body. The two points in the space are lined up perpendicular to the body surface. Energy is applied to heat the space, so as to increase the speed of reaching a steady state of heat flow from the body. When the steady state is achieved, the temperature at both of the points is equal and this temperature is assumed to equal the core body temperature.
U.S. Pat. No. 7,249,883 to Kuroda et al., whose disclosure is incorporated herein by reference, discloses a method for measuring a core body temperature from temperature measurements made by two external heat flux sensors. The external heat flux sensors are configured to have different heat flow resistivities. Varying resistivities may be obtained by several methods, including varying the thickness of insulation between the pairs of temperature sensors in each heat flux sensor.
Correlations between external and peripheral temperatures with the core body temperature are described by Fullbrook in “Core temperature measurement: a comparison of axilla, tympanic membrane and pulmonary artery blood temperature,” Intensive Critical Care Nursing, October 1997, 13(5):266-72, whose disclosure is incorporated herein by reference.